Table of Contents Author Guidelines Submit a Manuscript
Advances in Civil Engineering
Volume 2018 (2018), Article ID 9750480, 8 pages
https://doi.org/10.1155/2018/9750480
Research Article

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

1School of Civil Engineering and Architecture, Chongqing University of Science and Technology, Chongqing 401331, China
2Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58108-6050, USA
3Chongqing Key Laboratory of Energy Engineering Mechanics & Disaster Prevention and Mitigation, Chongqing 401331, China

Correspondence should be addressed to Baoyun Zhao; moc.361@666nuyoab

Received 2 October 2017; Revised 1 January 2018; Accepted 8 February 2018; Published 19 March 2018

Academic Editor: Hang Lin

Copyright © 2018 Baoyun Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus and elastic modulus first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.